Fix a minor bug about generate_video (#879)

* Fix a minor bug about `generate_video`

`fps` is not passed to `images_to_video`

* Update common.py

Follow black format

Author: Jiayuan-Gu

habitat_baselines/utils/common.py

@@ -394,7 +394,9 @@ def generate_video(
     )
     if "disk" in video_option:
         assert video_dir is not None
-        images_to_video(images, video_dir, video_name, verbose=verbose)
+        images_to_video(
+            images, video_dir, video_name, fps=fps, verbose=verbose
+        )
     if "tensorboard" in video_option:
         tb_writer.add_video_from_np_images(
             f"episode{episode_id}", checkpoint_idx, images, fps=fps